User blog comment:TrinityFlare/My New PvP Team.../@comment-31800919-20170623015810

Since Generation VI, flinch chances do not stack with items. Air Slash no longer gets a higher flinch rate because of King's Rock/Razor Claw, and neither do any other moves that already have a flinch chance. This includes Dark Pulse, Rock Slide, Iron Head and such. So you are better off using focus sash, sky plate, or miracle seed on that shaymin